There has been a rapid development of wireless technology during the last decade. As of November 2011, there were more than 5.9 billion mobile phone users worldwide. (See e.g., Reference #1). As the number of users utilizing wireless devices increases, concerns have been raised with regard to the risk associated with the use of radio frequency (“RF”) transmitting devices (e.g., mobile or cellular telephones). The concern can be even greater when considered along with the surge of the cancer incident rates over the past several decades. Mobile phones, and other RF transmitting devices, operate via a bidirectional transmission of radio waves at ultrahigh frequency (e.g., the radio to microwave range). Typical mobile phone communication systems operate between 800 MHz and 2700 MHz. At these frequencies, RF waves are supposedly non-ionizing (e.g., they do not carry enough energy to break chemical bonds). Nonetheless, being exposed to the RF radiation can result in increased heating of tissue via Joule and Dielectric heating mechanisms. Additionally, the ultimate effect of prolonged exposure to the use of an RF device is currently not known.
Specific Absorption Rate (“SAR”) measures the rate at which energy from electro-magnetic (“EM”) waves is absorbed by the body, and can be relevant in the safe usage of wireless devices, especially RF devices. (See e.g., Reference #2). SAR can depend on several factors, which can include the antenna and its position, the body's morphologic factor, the distance between the transmitting device and the head which can vary between individuals, and the power output of the device. Recent investigations have reported an increased incidence of malignant tumors in the head, brain, ear canal and parotid gland in connection with mobile phone usage. However, the difficulty associated with interpretation of the data from epidemiological studies has been described (see e.g., Reference #3), and the risk of cancer could not be confirmed. (See e.g., Reference #4). Studies have also shown an increase in evidence that RF EM fields (e.g., RF EM fields emitted by mobile phones) can potentially alter brain physiology (see e.g., References #5-11), and that a local exposure of tissue in the periphery and interior of the brain of young children is on average higher in comparison to adults. Assuming that there is no age dependence on the dielectric properties of the tissues, the reason is considered to be the closer vicinity of the RF currents to the brain of the child compared to the adult due to the age-dependent changes in proportions of the facial and skull regions. Additionally, the increased usage of mobile phones in children, as compared to adults, can also be a factor. While these results show that the RF radiation can alter the brain physiology, other studies suggest that a more detailed, qualified, analysis of the exposure and heating of the brain and its sub-regions is needed. (See e.g., Reference #12).
To quantify safety of wireless communication devices, cell phone makers and researchers model the wireless device using a numerical simulation such as the Finite-Difference-Time-Domain (“FDTD”) method to visualize and quantify the resulting EM and SAR distributions inside a human body model. This simulation can be conducted with different orientations of the wireless device relative to an “average” human model. This simulation, however, can be innately flawed as it can be difficult to confirm that the actual induced fields inside the subject are the same as the simulated fields. While these simulations can provide some information regarding the local SAR distribution in the “average” human brain, it is not clear if they provide a realistic picture with regard to the actual exposure that individuals experience when using RF-transmitting devices, and more importantly, whether the device is safe for use. In addition to the utilization of simulation software to evaluate the local SAR generated by wireless communication devices, vendors also use homogeneous gel phantoms with temperature probes implanted in them. The wireless transmitting device can be activated next to the gel phantom, and the temperature change due to Joule and Dielectric heating mechanisms can be recorded. Even though the temperature is correlated with tissue damage, the use of a simple setup with a homogeneous gel phantom to mimic the complex anatomy of the human brain is too simplistic, and the conclusions that can be drawn with regard to the safe use of a specific device based on this type of testing can be misleading.
Generally, for a brief application of RF energy, the exposure duration may not be long enough for significant conductive or convective heat transfer to contribute to tissue temperature rise. In such case, the time rate of the rise in temperature is proportional to SAR. For longer exposure durations (e.g., when using mobile phones), RF energy-induced temperature rise can depend on the animal or tissue target, and their thermal regulatory behavior and active compensation process. For local or partial body exposures, if the amount of the RF energy absorbed is excessive, temperature rise and local tissue damage can occur. Under moderate conditions, a temperature rise on the order of 1° C. in humans and laboratory animals can result from an SAR input of 4 W/kg. However, this temperature rise falls within the normal range of human thermoregulatory capacity, and the heat increase alone cannot explain tissue damage. Nonetheless, under certain ambient environmental conditions where the temperature and humidity are already elevated, or where the heat capacity of the tissue is elevated and perfusion is low, the same SAR could produce body temperatures that reach well beyond normal levels permitted by the 1° C. increment, which can precipitate undesired heat-stress-related responses. The central premise of the exposure guidelines to protect exposed subjects against temperature increases could be eclipsed, breaching the temperature threshold for induction of adverse thermal effects. While the mechanism(s) of tissue heating which result from RF exposure are complex, it is possible that due to their complexity, and the limitations of our scientific knowledge, some mechanism(s) responsible for producing a significant effect(s) are still unknown. (See e.g., Reference #2).
Thus, it may be beneficial to provide exemplary systems, methods and computer-accessible mediums which are non-simulation based, which can quantify and assess the SAR-related risk with regard to RF transmitting device usage, and which can overcome at least some of the deficiencies described herein above.